The Gene Targeting and Transgenic Mouse (GTTM) Share Resource assists Cancer Center members who use animal models in constructing and managing genetically altered mouse strains. It is operated by Dr. Sang-Yong Kim, a microinjection expert, and is supervised by Dr. Jacek Skowronski (Associate Investigator). The GTTM Shared Resource is equipped with two microinjection stations and support equipment that allow for generation of transgenic mice by direct DNA injection into fertilized zygotes and construction of chimeric mice using Embryonic Stem (ES) cell technologies. Service provided by the GTTM Shared Resource will initially include generation of transgenic animal models by pro-nuclear injection, maintenance of ES cell line stocks capable of efficient germline contribution for use in gene targeting experiments, generation of chimeric mice with genetically altered ES cells, and mouse embryo cryopreservation services. Funds are requested for the equipment necessary to establish ES cell culture and embryo cryopreservation services. The GTTM Shared Resource was recently established to meet the rising demand for these services from the Cancer Center members that use animal models that use animal models in their research. We predict that the GTTM Shared Resource will become an important resource for cancer researchers at CSHL, further promoting scientific interactions between CSHL investigators, and at other research institutions around the world.